Why Congress, Bush disagree on waterboarding of terror suspects

But there are also broader concerns about such techniques being deemed illegal by Congress. While waterboarding was used against three high-level Al Qaeda suspects, many of the other controversial techniques were routinely used on a much larger group of detainees, according to government reports.

The quality of that gathered information is an issue lurking in the background of several of the highest profile terror cases in the US legal system. Detainees at the Guantánamo terror prison camp are asking the US Supreme Court for an opportunity to challenge the legality of their detention by having federal judges test the veracity of allegations made against them.

The Bush administration is fighting to prevent any examination of the quality of US intelligence information in a court of law. Such an inquiry might, in turn, lead to broader questions about the legality of US interrogation methods.

Similar questions about the quality of information and legality of interrogation techniques are expected to arise at US military commissions that are set to conduct war-crimes trials later this year at Guantánamo.

Supporters of the Army Field Manual approach say information obtained through more benign methods of questioning yield more reliable information. Gen. David Petraeus, commander of US forces in Iraq, made this point in a letter to the troops last year. "Certainly extreme physical action can make someone 'talk;' however, what the individual says may be of questionable value," he wrote.